Summary: On one level, poverty exacerbates gender disparities. Inequalities between girls and boys in access to schooling or adequate health care are more acute among the poor than among those with higher incomes. These disparities disadvantage women and girls and limit their capacity to participate in and benefit from development. On another level, gender inequalities hinder development. Evidence brought together in this report shows this unambiguously. A central message is clear: ignoring gender disparities comes at great cost-to people's well-being and to countries' abilities to grow sustainably, to govern effectively, and thus to reduce poverty. This conclusion presents an important challenge to the development community. What types of policies and strategies promote gender equality and foster more effective development? This report examines extensive evidence on the effects of institutional reforms, economic policies, and active policy measures to promote greater equality between women and men. The evidence sends a second important message: policymakers have a number of policy instruments to promote gender equality and development effectiveness. But identifying what works requires consultations with stakeholders-both men and women-on key issues and actions. This points to a third important message in this report: to enhance development effectiveness, gender issues must be an integral part of policy analysis, design, and implementation.